This invention relates to the retention of PC cards in card holders and, more particularly, to a system of preventing unintended disengagement by resiliently biasing a retainer into a pathway along which the card is removed from the holder.
PC cards are used in various types of electronic devices. Such devices include notebook computers and various types of devices for reading bar codes and other symbologies. The reading devices include scanners and digital cameras. In bar code scanners, bar code data may be stored in a compact flash card preparatory to transfer to a host computer. The transfer may occur by wireless communication, i.e. radio frequency communication, an infrared signal, or use of a modem. Digital cameras are sometimes used for reading two-dimensional symbologies, which are in effect a two-dimensional version of the standard one-dimensional bar code. Digital cameras are also used for broader purposes, such as high quality photography of subjects unrelated to bar codes.
Reading devices are frequently used in factory or warehouse environments where all or a portion of the reader, such as a computer or communications device, is mounted on a forklift or other vehicle or on a wall or other support structure that is subjected to vibrations. In the case of a vehicle mounting, the vibrations are due at least primarily to the operation of the vehicle. In the case of a support structure mounting, vibrations may be experienced because of the operation of machinery and other activity in the vicinity of the structure.
A problem that has been encountered in connection with the use of PC cards in environments subject to vibrations is the disruption of a reading or communication process caused by unintentional movement of a PC card out of position in its holder. Such movement disengages the card from a connector that electronically connects it to the system. If the unintended disconnection of the card occurs during a card memory writing process or the transmission of data, data may be lost. This results in the added expense of personnel time spent in recollecting the data. In some situations, it may not be possible to recollect the data. For example, in a warehouse environment, the data might include the identification of shipping units that have left the warehouse and are on their way to their destinations.
Currently available mounting mechanisms for PC cards have the drawback of not providing for protection against unintended disconnection of cards when the device is subjected to vibrations or similar disturbances. The conception of the present invention began with the applicant""s recognition of the need for a mechanism that would prevent unintended disengagement of a card from its connector and also allow or facilitate removal of the card when removal is desired.
A subject of the invention is a device for retaining a PC card in an engaged position in a card holder that permits movement of the card out of the engaged position along a pathway. According to an aspect of the invention, the device comprises a retainer having a blocking portion biased to extend into the pathway to prevent unintentional movement of the card along the pathway out of the engaged position when the holder is subjected to vibrations. The retainer is yieldably biased to allow the blocking portion to be deflected out of the pathway for desired insertion or removal of a card. When it is desired to remove a card, a positive force may be deliberately applied to the card to move the card out of its engaged position. The movement of the card deflects the blocking portion. Similarly, movement of the card into the holder toward the engaged position deflects the blocking portion.
The retainer may be used in connection with a holder from which cards are removed manually. In such case, the positive force is applied directly by grasping and pulling on the card or by pushing the card. The retainer may also be used in connection with a card holder that has an ejector operable to move the card along the pathway from the engaged position to an ejected position. In such case, operation of the ejector and the resulting movement of the card deflects the blocking portion.
Whatever the manner of intended removal of the card from the holder, the retaining device may include a number of preferred features. Preferably, the blocking portion of the retainer engages a corner portion of the card to prevent unintentional movement of the card. Also preferably, the retainer comprises a resilient finger, and the blocking portion is provided by an end portion of the finger. In the preferred embodiment, the finger includes a main portion that extends substantially parallel to the pathway and has a first end mounted adjacent to the holder and an opposite second free end. A hook portion is carried by the second end. An outer end surface of the hook portion engages the corner portion of the card.
The material from which the finger is made and the configuration and mounting of the finger may be varied considerably. In the currently preferred embodiment, the finger is made from a flexible nylon material. It is anticipated that the card holder will normally be mounted on a circuit board. Preferably, the first end of the finger will be mounted on the board adjacent to the holder. For one type of holder, the preferred form of the retainer includes a bracket that is integral with the finger. The bracket extends around the holder and is secured to the circuit board by a plurality of fasteners. The fasteners also secure the holder to the board. This is an efficient and secure way of mounting the retainer.
Another subject of the invention is a method of preventing unintentional movement of a PC card along a pathway out of an engaged position in a card holder when the holder is subjected to vibrations. According to an aspect of the invention, the method comprises yieldably biasing a blocking portion of a retainer to extend into the pathway to prevent the unintentional movement. When it is desired to remove the card from the holder, a positive force is applied to the card to move the card out of the engaged position. The method includes allowing movement of the card to deflect the blocking portion out of the pathway. It also includes inserting a card into the holder and allowing movement of the card toward the engaged position to deflect the blocking portion out of the pathway.
Preferably, the method comprises positioning the retainer to engage a corner portion of a card in the engaged position. Also preferably, positioning the retainer comprises mounting a first end of a flexible finger adjacent to the holder, and positioning an end surface of a hook carried by an opposite second free end of the finger to engage the corner portion.
The apparatus and method of the invention solve the problem discussed above of unintended disengagement of a PC card from its connection to a system and consequent disruption of the symbology reading or other procedure being carried out by the system. The retainer of the invention provides a simple and cost effective means for preventing unintentional movement of the card. At the same time, the retainer in no way interferes with the normal procedures for inserting cards into their holders and removing the cards therefrom when removal is desired.
The advantages and features discussed above and other advantages and features will become apparent from the detailed description of the best mode for carrying out the invention that follows.